Russian METAR question
 

I have here a Moscow METAR.

It has a 6 digit numerical code imediately after the Cloud Cover values.

The number is 670000.

Anyone know what it means??

I think you'll have to post the entire report in order for us to see the context.

Would it be a reasonable guess that it's not a recent METAR?

I can't find any reference for Russia, but WMO Manual on Codes indicates that the Ukraine uses icing and turbulence groups in METARs as in TAFs. In that case 670000 would mean severe icing from the surface to the top of cloud.

UUEE 191920Z 192106 VRB03MPS 3000 BR OVC007 TEMPO 2106 0900 SHSNRA
FZRA SCT003 BKN006 SCT012CB 640000=

It's about icing layers
 

630004

The first digit is always a 6.

The second digit it the type of icing...3 = light icing in precip.

The next 3 digits represent the base of the layer in 30's metres (or 100's of feet)... 001 = 30 metres; 100 would mean 3000 metres.

The last digit is the thickness of the icing layer in feet. 4 = 4,000 feet or 1200m.

There are also codes for other types of weather, but the 6 indicates in this case it is icing.